Cyto genetical studies in the inbred lines of radish raphanus sativus var radicola and their hybrids part 2 genetic regulation of chiasma frequency
Cytologia 42(2): 273-278
ISSN/ISBN: 0011-4545 Accession: 005082189
Mean chiasma frequency at diakinesis was studied in 2 inbred lines of radish (R. sativus L. var. radicola Pers.), 'LS-337/24 (I12-' and 'LS-337/25 (I12)', and their F1, F2 and backcross hybrids. The number of chiasmata per cell was less in the inbred lines (homozygotes) than in their F1 hybrid (heterozygote). F2 hybrid plants, raised from a single plant of F1 hybrid, demonstrated a wide distribution of this character, which had polygenic control. The value of mean chiasma frequency in F2 hybrid occupied an intermediate position between the lines and the F1 hybrid. Backcross hybrids showed a marked decline in chiasma frequency when compared to F1, indicating an influence of respective inbred lines on this character. The optimum level of chiasma frequency is a function of heterozygosity of genes and its distribution is controlled polygenically. The genetic system regulating the formation and distribution of chiasmata in radish was discussed.